Cab Roof Repair
 

I'm finally starting cab restoration on Earl. I got most of the old seam sealer (what there was left) out of the drip edge and can now see that the roof panel is rusted through just about all the way around the front and sides just where it meets the drip edge. I think the roof is solid, but I need to get behind the edges at the drip rail to clean up any inside rust and get the roof panel edges ready to weld back to the drip edge inside edge.

One thought I had was to cut the roof panel totally off at the rear seam. That would allow me to clean up the inside and outside of both the roof panel and the drip edge area. In addition, it will be a lot easier to patch the roof panel edge so it's ready to go back on.

Am I making a big mistake thinking about removing the roof panel? Is there some show-stopping problem lurking in the future when I try to weld it back on? Should I cut the panel off right at the rear seam, or somehow try to separate the original panel joint? Any comments would be welcome before I get out the cutoff tool.

Hi George

I would try and drill out the spot welds from inside the cab and seperate the original joint
The tricky bit will be the box section above the windscreen but if its rusted through then it may be OK
If you cut it off above the seem I think it may be hard to weld back on

Stephen

George -

I also think that drilling out the spotwelds the separating the joint would be the best method. The spotwelds for three sides of the roof are outside on the drip rail, so they are simpler to find and easier to drill. How to drill out the spotwelds of the rear seam accross the cab back seems problematic. I would get hold of a short right-angle drill, use pilots first, then drill out to size. A spotweld drill doesn't look like it will fit in there very well.

The biggest worry I would have is dealing with any preload that may be in the cab itself. The cab roof is holding everything in its correct geometry. Once removed, the whole cab/pillar structure is free to move. This happens to many in a chop job with sometimes disastrous results.

To be safe, I would weld 4 temporary diagonals (12-18 long) accross the inside jamb corners (2 from above each door to above windshield and 2 from above each door to above rear window) to freeze the shape by triangulating the corners of that rectangle. I would drill out those inside seam welds that the diagonal will cover first, for access reasons. Then, after the diagonals are in, drill out the rest of the spotwelds and separate the roof.

One other nice thing about drilling out the spotweld is that the drilled holes remain in each piece to help ensure all goes back together correctly.

Make sense? Good luck. :-D

No problem drilling out spot welds around the front and sides - they don't exist anymore. As for the rear seam - I agree. It looks to me like it would be quite difficult to get in there with even a right angle drill.

Randy - the roof is basically not attached to the cab on three sides. I figure I'll have to square everything up using the doors and careful measurements if I'm going to use this cab. On the other hand, there's not much to loose by getting out the cutting wheel, is there?

Wow, you got more guts than I do! My first question is if the damage to the existing sheet metal is structural. If so, you have little choice than to remove and replace the steel.

If not, I would look hard at some of the rust converters. The main idea is that if moisture and oxygen can not reach the steel, it will not rust. Rust converters convert the rust to an insoluble coating that keeps both moisture and oxygen out, just like the patina on brass or copper.

In some converters the principal chemical is phosphoric acid which reacts with the steel and rust to form a phosphate coating, which is more of a rust retarder than a rust stop. The ideal converter is one that has a ph of 2 to 2.5, and contains tannic acid.

Tannic acid is what museums use to stop rust in their iron artifacts. It forms a durable tannic film that is virtually insoluble. It is also expensive - you get what you pay for.

You have to coat both sides of the metal or moisture will seep through small pin holes in the metal and lift your paint, causing more corrosion. Once coated, you should not sand the item, for a smooth coat you have to recoat with sanding primer, or even body putty.

On my 59, I am drilling 3/4" holes in out of the way places in order to reach the inside of the hinge piller and cab supports, and such. I use a 1 gallon garden sprayer inserted into the hole to spray the converter. I waste a lot of it, but want to insure every square inch of the steel is coated. I have some 3/4" rubber plugs to seal the holes when I am done.

I used the metal wand of this sprayer to coat the inside of my cab roof rails and a brush to do the outside. Do whatever repairs you must before you use the converter as coated steel is very difficult to weld, you have to grind the coating off and it forms a very hard surface, much harder than the underlying steel.

You are aiming for a much finer restoration than I am - I just want a daily driver. However, if your cab is still structurally sound, a rust converter and putty or lead can save you months of work in an area no one will ever see.

George -

I didn't know you had gone that far. Yes, I agree, if the roof already is detached on three sides, you've nothing to lose by grinding off the fourth side. I'd try to leave enough of the seam flange to weld it back together later (if you use that roof).

George
If the roof metal is gone beyond saving, and there is not enough to reattach, you may want to start looking for a VW Beatle/Super Beatle. The roof size and shape lend themselves to the pickups.

PS: Also there is also the chance of the "One of a kind, Bone Stock, Roadster Pickup".

Another thought

If you can't get to the spot welds with a drill try using the side of a stone with a die grinder.

I am contemplating the same thing when I fix my roof. A few of us were brainstorming on this top level government project at work. We thought the best idea was to get an angle grinder. Then with a grinding wheel that is about .25" thick, grind out the spot welds making notches using the edge of the wheel. So you would end up with a .25" notch where a weld was. That would atleast leave the two flanges, which gets covered by the roof liner to weld back on instead of the outside skin of the cab. You could also use vice-grips to hold the flanges together for alignment.

I tried that on my old cab, and the stone was gone before two spot welds were gone. Is there a place to good quality grinding stones?

Get some from a proper Engineering supply house rather than a general tool store

If you know a Toolmaker who works with press tools or injection moulding tools they should be able to point you in the right direction

George,
If your roof is basicaly in good condition, except for the front edge, I would seriously consider cutting the damaged steel out from the out side then cleaning the back side by blasting or chemical, then place patch inside and weld on the outside. The weld in the drip edge can be covered by the seam sealer down the road.
Having done a chop top, if I didn't have to remove the roof I wouldn't.
Just my opinion.
Good luck
Mike

i agree with mt54 dont remove the roof unless you absolutely need to if the roof skin itself is bad midfifty has a fiber one in standard and in 2" drop. if you were to do something like that i would cut above it and then deal with the spot welds but only if you were going to replace the entire roof panel.
on another note i just got some spot weld removers from htp america in arlington heights, ILL they are like drill bits with a small pilot and are about 3" long

George.

I have a nice roof section. Asking $300.00 and this includes a windshield.

Let me know
Kevin Bigwin

If interested, I have a roof section available for nothing.

I think it is in good condition, I would have to look a bit closer as it was not something I was interested in.
It has been cut from the cab in the area of the windows midsections.
I did notice that the inner lip (where the visors connect) has been hacked out.
Downside: I am in Missouri. I do drive up to Cincinatti about once a month. If you could wait till my next trip, I would be happy to pass it on. Next trip planned for Oct 1 weekend.